1. Field of the Invention
The invention relates generally to a protective composite material which is impervious to a broad range of hostile or damaging environments, and more particularly to a three-part laminate material for forming protective bags or cases.
2. Description of the Related Art
Bags or cases for carrying and storing equipment such as guns, cameras, video equipment, scientific instruments, military devices and the like, are used under a variety of adverse physical conditions. Depending on the particular device involved, the adverse conditions may include high temperatures, exposure to rain or moisture, exposure to sun rays, and exposure to dust or other particulate pollutants. Prior art cases are typically made of a semi-rigid material which provides protection from impact, water, spray and dust. For example, U.S. Pat. No. Re 33,402 discloses a typical protective carrying case for a video cassette recorder or other electronic device. The carrying case comprises upper and lower halves which are formed of a high-impact material and are integrally coupled to each other. Each of the two halves has a cover means hingedly connected thereto for accessing the cassette door of a video cassette recorder and electrical connections, respectively. Devices such as these generally are bulky and cannot be compacted or folded for storage. Furthermore, these devices tend to trap moisture inside which may corrode or degrade the item being stored. Moreover, semi-rigid cases generally tend to be relatively expensive to manufacture.
Another type of prior art device consists of a protective bag which is made simply of a non-porous plastic film. These bags, for example a polyethylene bag, tend to be more lightweight than the semi-rigid cases and are very compact while providing excellent protection from dust and liquids. However, they provide no impact resistance. Furthermore, these bags trap moisture and permit the interior of the protective bag to become very hot if exposed to direct sunlight, due to a greenhouse effect, which may result in damage to the item stored in the protective bag.
The limitations of the prior art can be shown by an example involving an expensive item such as a video cassette camera. A video camera taken on a small boat on the ocean may be exposed to rain, salt water spray, fine beach sand, heat from the sun, and impact from the abrupt movement of the boat as it encounters ocean waves. A protective case such as the one disclosed in U.S. Pat. No. Re 33,402 might protect the camera from impact but the case is likely to be damaged itself if it becomes saturated with water or is soiled by dirt and grime on the boat. An additional disadvantage is that the protective case of Re 33,402 cannot be compacted for easy stowage. Similarly, a clear plastic bag would provide moisture and dust protection. However, no impact protection would be provided and the bag would become very hot allowing for easy puncturing when the bag is exposed to direct sunlight. Also, the heat generated inside the bag may result in damage to the equipment stored therein. Under such circumstances, neither the plastic bag nor the protective carrying case disclosed in Re 33,402 would be acceptable. Further, neither the carrying case nor the typical plastic bag would float if the case or bag containing the camera was inadvertently tossed overboard.
U.S. Pat. No. 4,439,473 discloses an open-cell foam coated fabric having a breathable fine cell foam coating adhered to a fabric substrate. This material may be used to form bags and cases of varying sizes and shapes. The foam coating is made of an open-cell foam polymer lattice and a hydrophobic material which coats substantially all of the surfaces of the polymeric lattice and renders the breathable foam coating waterproof. However, the foam coated fabric disclosed in this patent application does not disclose a material which is capable of preventing the accumulation of dust and other fine particles. Rather, both an open-cell foam material and a fabric substrate are especially susceptible to the accumulation of dust.
Because of these and other shortcomings in prior art bags and cases, there is a need for a material for bags and cases which is breathable and water repellent, while still providing protection for the contents of the bag or case by absorbing impact and preventing the accumulation of dust and other unwanted particle accumulations.